HILTON HEAD ISLAND, S.C. -- Save the fitness trailer for the rest of the PGA Tour, Carl Petterson knows he's fine the way he is.

Petterson used another fast start for a 2-under 69 and a five-shot victory over Zach Johnson on Sunday at the RBC Heritage. Pettersson has never fit the tapered, powerful build made popular by Tiger Woods and copied by scores of young players.

The one time the 34-year-old Pettersson did slim down and lost 30 pounds, he also lost his winning golf swing.

"Ultimately, just cause you don't look like an athlete doesn't mean you're not an athlete," Pettersson said. "We're not running a marathon out here, we're walking 18 holes."

And no one walked them better this week at Harbour Town Golf Links than Pettersson. He finished at 14 under to win his fifth PGA Tour title and first since 2010. Pettersson also tied countryman Jesper Parnevik for most ever on tour by a Swedish player.

"It was great," said Pettersson, now a U.S. citizen. "I didn't want to put too much pressure on myself, so I kind of downplayed the whole thing. But getting off to a birdie on one was great."

Pettersson, second in the Houston Open two weeks ago, earned $1,026,000.

Top-ranked Luke Donald needed to finish eighth or better to retain his ranking, but tied for 37th and will fall behind Rory McIlroy.

Johnson shot a 70 to finish second at 9 under, while Colt Knost's chances for his first PGA Tour title fell apart with a 74. He was third at 8 under.

Masters winner Bubba Watson and most of the world's best took the week off to recover from the year's first major

No one, though, was catching Pettersson in this one. He rolled in a 24-footer on No. 1 to get things started with a birdie. He added another birdie, from 16 feet on the par-3 fourth hole, then two-putted from 40 feet on the par-5 fifth to go up by four shots. When Johnson took bogey at No. 10, Pettersson was five strokes in front and cruising.

Pettersson used a run of five straight birdies on the front side Saturday to gain the lead. He was 13 under on the front nine the four days.

"I like all the holes," he said. "I don't have one hole on the front nine where I feel awkward over the tee shot or second shot."

He also didn't feel too bad on the greens, needing just 104 putts over 72 holes.

Knost was on top after Thursday and Friday and felt good as part of the final pairing. But those nerves Knost acknowledged Saturday were apparently back again in the final round.

He missed an 8-foot putt for par and made bogey on No. 1 for a second straight round to drop three shots behind Pettersson. And just like Saturday, Knost fought back with a birdie on the second hole -- he made eagle there in the third round -- to close in on Pettersson.

However, Knost's chances ended, though, a hole later with a horrible drive out of bounds left on No. 3 that led to a triple-bogey seven and left him five shots behind and out of contention.

When Knost flew his approach to the 12th green way left, he simply stood in the fairway and stared straight ahead, hands on hips, in disbelief.

"I hit it good this weekend, but the one swing (on No. 3) got me in trouble," Knost said. "I made 7 and that was kind of it."

Pettersson didn't let Knost's troubles affect his focus.

"He had a tough time out there," Pettersson said. "But there were still other guys with a chance."

Johnson, four strokes behind Pettersson at the start, tried to make a charge with birdies on the second, fourth and fifth holes. Johnson closed to three shots when he birdied No. 15 and Pettersson had his first bogey of the day moments later.

But Johnson ran out of steam on the 16th hole when he drove into a waste bunker and took bogey. Still, it was Johnson's best showing of the year and first top-10 finish since January.

"There were a couple of bumps along the road, but a lot of positives," Johnson said. "Certainly some things that I can learn from."

Donald was largely resigned to surrendering No. 1 when he woke up early for his 9:46 a.m. start time, more than four hours before the final group of Pettersson and Knost teed off.

Donald's round began badly with a double bogey at No. 1. He worked his way back with birdies on the fifth and sixth hole and that's where he stayed. Donald ended a four-week run at No. 1 that began after he won the Transitions Championship last month.

Donald said he's proved he's among the world's best and is confident he'll stay in that conversation, no matter where he's ranked. "Now, my focus is winning tournaments," he said.

Donald headed the list of four golfers among the 20 who followed the Masters with Harbour Town. World No. 13 Webb Simpson finished at 4 over while No. 14 Matt Kuchar, two strokes from the playoff in third at Augusta National, also was way off the pace at 3 over. No. 18 Bill Haas did not make the cut.

Pettersson's last victory came at the RBC Canadian Open in 2010 and this win was likely just popular with first-year Heritage sponsor Royal Bank of Canada. The financial institution, along with the Boeing Co., stepped in last June to back the cash-strapped event which was in danger of disappearing without such support.Pettersson remembers in 2009 feeling like he needed to trim down to play better. He worked out more, ate right, dropped 30 pounds -- and couldn't swing the club. He vowed to beef up and rediscover his game. The regimen?

"Well, you drink 10 beers and (eat) a tub of ice cream before bed," Pettersson said. "That puts it on quickly."

Comfortable in his skin again, Pettersson went to work on his game. Things perked up this season with a second place at the Sony Open in January and the showing in Houston earlier this month. "It's fun to play again and I kept the weight on," he said.

With a win under his belt, Pettersson doesn't expect to change anything, even his (lack of) fitness routine.

"Maybe," Pettersson says, "some of these guys are overdoing it."

Divots: Sean O'Hair played by himself as Sunday's first tee time and finished a 2-over 73 in one hour, 55 minutes. ... 2010 champion Jim Furyk was a stroke off the lead Thursday with an opening 68. Furyk was only able to improve one stroke the final 54 holes, which was good enough to tie for eighth, his sixth top-10 here in the last nine appearances. ... Brian Harman, a 25-year-old pro from nearby Savannah, Ga., had a horrible final eight holes during his round of 82. Harman had four bogeys, two double bogeys and a triple bogey during that stretch.